AC generator for vehicle

ABSTRACT

The present invention provides an automotive alternator enabling a brush replacement operation to be improved by making a cap covering an opening portion for brush replacement formed in a case insertable to simplify removal and replacement of the cap. 
     A brush holder through which a brush insertion aperture is disposed and into a head portion of which a cover is fitted is disposed inside a case such that an aperture direction of the brush insertion aperture is perpendicular to an axial direction of a shaft, and a brush is disposed so as to be held inside the brush insertion aperture and slide in contact with a slip ring fixed to the shaft. An opening portion for brush replacement is formed in a portion of the case facing the cover, and a cap is insertably mounted to this opening portion.

TECHNICAL FIELD

The present invention relates to an automotive alternator driven by aninternal combustion engine, for example, and particularly relates to acase construction for improving brush replacement in a brush holdingapparatus.

BACKGROUND ART

Generally, a brush holding apparatus in an automotive alternator ismounted internally in a tightly-closed case, making it necessary todismantle the case during brush replacement, thereby making workabilityextremely poor.

Thus, automotive alternators in which an opening is disposed in aportion of the case facing the brush holding apparatus, enabling thebrushes to be changed through the opening, have been proposed inJapanese Utility Model Laid-Open No. SHO 51-87205, Japanese PatentLaid-Open No. SHO 51-66409, etc., for example.

FIGS. 29 and 30 are a longitudinal section and a plan, respectively,showing a vicinity of the brush holding apparatus of the conventionalautomotive alternator described in Japanese Patent Laid-Open No. SHO51-66409, for example, and FIG. 31 is a perspective showing a brushassembly used in the brush holding apparatus shown in FIGS. 29 and 30.

In FIGS. 29 to 31, a rotor 81 is fixed to a shaft 82 rotatably supportedin a front bracket (not shown) and a rear bracket 84 a by means ofbearings 83, being disposed inside a case 84 composed of the frontbracket and the rear bracket 84 a. Slip rings 85 are mounted to arear-end end portion of the shaft 82.

A stator 86 is constituted by: a cylindrical stator core 87; and astator winding 88 installed in the stator core 87, first and second endportions of the stator core 87 being held between the front bracket andthe rear bracket 84 a, the stator 86 being disposed so as to surroundthe rotor 81.

A brush holding apparatus 89 is constituted by: a brush body portion 90through which a pair of brush-housing angular apertures 90 a aredisposed; and a pair of brush assemblies 95 in each of which a brush 91,a pigtail 92, a brush spring 93, and a brush terminal 94 are assembledintegrally. This brush holding apparatus 89 is mounted to the rearbracket 84 a by securely fastening the brush body portion 90 to an innerwall surface of an end wall of the rear bracket 84 a by means of a screw96, inserting the brushes 91 of each of the brush assemblies 95 into thebrush-housing angular apertures 90 a, and securely fastening the brushterminals 94 to the brush body portion 90 by means of screws 97. Thus,the brushes 91 are forced into contact with the slip rings 85 by thebrush springs 93.

In addition, an opening 98 for brush replacement is disposed through aportion of a side wall of the rear bracket 84 a facing the brush bodyportion 90. A cover 99 is securely fastened to an outer circumferentialsurface of the side wall of the rear bracket 84 a by means of screws 100so as to cover the opening 98.

A brush replacement operation of the conventional automotive alternatorconstructed in this manner will now be explained.

First, the cover 99 is removed by removing the screws 100. Then, thescrews 97 are removed and the brush assemblies 95 are pulled out throughthe opening 98. Next, the brushes 91 of new brush assemblies 95 areinserted into the brush-housing angular apertures 90 a, and the brushterminals 94 are securely fastened to the brush body portion 90 by meansof the screws 97 while pressing the brush springs 93. In addition, thecover 99 is placed over the opening 98 and securely fastened to the rearbracket 84 a by means of the screws 100, completing replacement of thebrushes 91.

However, in this conventional automotive alternator, because the cover99 is mounted to the rear bracket 84 a by means of fastening by thescrews 100, one problem has been that removal and replacement of thescrews 100 is required in a narrow engine compartment, lowering brushreplacement work efficiency.

SUMMARY OF THE INVENTION

The present invention aims to solve the above problem and an object ofthe present invention is to provide an automotive alternator enabling abrush replacement operation to be improved by making a cap covering anopening portion for brush replacement formed in a case insertable tosimplify removal and replacement of the cap.

In an automotive alternator according to the present invention, firstand second ends of a shaft are rotatably supported in a case, and arotor is fixed to the shaft and is rotatably disposed inside the case. Aslip ring is fixed to the shaft, and a stator is fixed to the case so asto surround the rotor. A brush holder through which a brush insertionaperture is disposed and into a head portion of which a cover is fittedis disposed inside the case such that an aperture direction of the brushinsertion aperture is perpendicular to an axial direction of the shaft,and a brush is disposed so as to be held inside the brush insertionaperture and slide in contact with the slip ring. An opening portion isformed in a portion of the case facing the cover, and a cap isinsertably mounted to this opening portion. Thus, an automotivealternator is provided in which removal and replacement of the cap issimplified, enabling the brush to be changed without dismantling thecase.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal section showing an automotive alternatoraccording to Embodiment 1 of the present invention;

FIG. 2 is a plan partly in section showing a rear bracket end of aninterior portion of the automotive alternator according to Embodiment 1of the present invention;

FIG. 3 is a plan showing a brush holding apparatus used in theautomotive alternator according to Embodiment 1 of the present inventionwith a cover removed;

FIG. 4 is a plan showing the brush holding apparatus used in theautomotive alternator according to Embodiment 1 of the presentinvention;

FIG. 5 is a front elevation showing the brush holding apparatus used inthe automotive alternator according to Embodiment 1 of the presentinvention;

FIG. 6 is a front elevation showing a brush assembly of the brushholding apparatus used in the automotive alternator according toEmbodiment 1 of the present invention;

FIG. 7 is a side elevation showing the brush assembly of the brushholding apparatus used in the automotive alternator according toEmbodiment 1 of the present invention;

FIG. 8 is a plan showing a cap used in the automotive alternatoraccording to Embodiment 1 of the present invention;

FIG. 9 is a side elevation of the cap shown in FIG. 8 viewed fromdirection A;

FIG. 10 is a side elevation of the cap shown in FIG. 8 viewed fromdirection B;

FIG. 11 is a perspective showing the rear bracket of the automotivealternator according to Embodiment 1 of the present invention with thecap mounted;

FIG. 12 is a perspective showing the rear bracket of the automotivealternator according to Embodiment 1 of the present invention with thecap removed;

FIG. 13 is a plan showing a cap used in an automotive alternatoraccording to Embodiment 2 of the present invention;

FIG. 14 is a side elevation of the cap shown in FIG. 13 viewed fromdirection A;

FIG. 15 is a side elevation of the cap shown in FIG. 13 viewed fromdirection B;

FIG. 16 is a perspective showing a rear bracket of the automotivealternator according to Embodiment 2 of the present invention with thecap mounted;

FIG. 17 is a cross section taken along line XVII—XVII in FIG. 16 viewedfrom the direction of the arrows;

FIG. 18 is a perspective showing the rear bracket of the automotivealternator according to Embodiment 2 of the present invention with thecap removed;

FIG. 19 is a plan showing a cap used in an automotive alternatoraccording to Embodiment 3 of the present invention;

FIG. 20 is a side elevation of the cap shown in FIG. 19 viewed fromdirection A;

FIG. 21 is a side elevation of the cap shown in FIG. 19 viewed fromdirection B;

FIG. 22 is a perspective showing a rear bracket of the automotivealternator according to Embodiment 3 of the present invention with thecap mounted;

FIG. 23 is a perspective showing the rear bracket of the automotivealternator according to Embodiment 3 of the present invention with thecap removed;

FIG. 24 is a plan showing a cap used in an automotive alternatoraccording to Embodiment 4 of the present invention;

FIG. 25 is a side elevation of the cap shown in FIG. 24 viewed fromdirection A;

FIG. 26 is a side elevation of the cap shown in FIG. 24 viewed fromdirection B;

FIG. 27 is a perspective showing a rear bracket of the automotivealternator according to Embodiment 4 of the present invention with thecap mounted;

FIG. 28 is a perspective showing the rear bracket of the automotivealternator according to Embodiment 4 of the present invention with thecap removed;

FIG. 29 is a longitudinal section showing a vicinity of a brush holdingapparatus of a conventional automotive alternator;

FIG. 30 is a plan showing the vicinity of the brush holding apparatus ofthe conventional automotive alternator; and

FIG. 31 is a perspective showing a brush assembly used in the brushholding apparatus of the conventional automotive alternator.

BEST MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments of the present invention will now be explainedwith reference to the drawings.

Embodiment 1

FIG. 1 is a longitudinal section showing an automotive alternatoraccording to Embodiment 1 of the present invention, FIG. 2 is a planpartly in section showing a rear bracket end of an interior portion ofthe automotive alternator according to Embodiment 1 of the presentinvention, FIG. 3 is a plan showing a brush holding apparatus used inthe automotive alternator according to Embodiment 1 of the presentinvention with a cover removed, FIG. 4 is a plan showing the brushholding apparatus used in the automotive alternator according toEmbodiment 1 of the present invention, FIG. 5 is a front elevationshowing the brush holding apparatus used in the automotive alternatoraccording to Embodiment 1 of the present invention, FIG. 6 is a frontelevation showing a brush assembly of the brush holding apparatus usedin the automotive alternator according to Embodiment 1 of the presentinvention, FIG. 7 is a side elevation showing the brush assembly of thebrush holding apparatus used in the automotive alternator according toEmbodiment 1 of the present invention, FIG. 8 is a plan showing a capused in the automotive alternator according to Embodiment 1 of thepresent invention, FIG. 9 is a side elevation of the cap shown in FIG. 8viewed from direction A, FIG. 10 is a side elevation of the cap shown inFIG. 8 viewed from direction B, FIG. 11 is a perspective showing therear bracket of the automotive alternator according to Embodiment 1 ofthe present invention with the cap mounted, and FIG. 12 is a perspectiveshowing the rear bracket of the automotive alternator according toEmbodiment 1 of the present invention with the cap removed.

This automotive alternator includes: a case 3 constituted by a frontbracket 1 and a rear bracket 2 made of aluminum, each being preparedinto a general cup shape; a shaft 6 rotatably disposed inside the case3, a pulley 4 being fixed to a first end portion of the shaft 6; aLundell-type rotor 7 fixed to the shaft 6; a stator 8 mounted to thecase 3, the stator 8 being held between the front and rear brackets 1and 2 so as to surround the rotor 7; fans 5 respectively fixed to firstand second end portions of the rotor 7; a pair of slip rings 9 fixed toa second end portion of the shaft 6 for supplying electric current tothe rotor 7; a brush holding apparatus 20 in which a pair of brushes 21sliding on a surface of each of the slip rings 9 are housed inside abrush holder 22; a rectifier 10 electrically connected to the stator 8for converting alternating current generated in the stator 8 into directcurrent; and a regulator 11 fitted onto the brush holder 22, theregulator 11 adjusting the magnitude of the alternating voltagegenerated in the stator 8.

The brush holder 22 is made of a resin such as a polyphenylene sulfide(PPS), etc. A pair of angular brush insertion apertures 22 a are formedso as to pass through the brush holder 22, and terminals 23 electricallyconnected to a battery (not shown) constituting an electric power supplyare formed integrally on the brush holder 22. Brush assemblies 24 areeach constructed such that a brush 21 and a brush terminals 25 areconnected by a wire 26, a spring 27 being disposed in a compressed statebetween the brush 21 and the brush terminal 25. The brush holdingapparatus 20 is constructed by mounting these brush assemblies 24 to thebrush holder 22 by inserting the brushes 21 inside the brush insertionapertures 22 a and securely fastening the brush terminals 25 to theterminals 23 by means of screws 28 from longitudinally outside thebrushes 21. Then, a cover 29 provided with a packing (not shown) on aninner wall surface is fitted into a head portion of the brush holder 22from longitudinally outside the brushes 21, shielding the fasteningportion between the terminals 23 and the brush terminals 25 and thebrush insertion apertures 22 a from the outside, thereby ensuring thatthe brush holding apparatus 20 is waterproof

The brush holding apparatus 20 constructed in this manner is mounted tothe rear bracket 2 such that the longitudinal direction of the brushes21 is perpendicular to an axial direction of the shaft 6. Thus, thebrushes 21 are pushed against the slip rings 9 by the force of thesprings 27 and slide on the slip rings 9 due to the rotation of theshaft 6. Furthermore, the brush holder 22 extends in a radial directionto a vicinity of an inner wall surface of a side portion of the rearbracket 2. An opening portion 30 for brush replacement is formed in arectangular shape in a portion of the side portion of the rear bracket 2facing the cover 29 of the brush holding apparatus 20 longitudinally(radially) outside the brushes 21.

The rectifier 10 is mounted to the rear bracket 2 in a planeperpendicular to the axial direction of the shaft 6 so as to overlap thebrush holding apparatus 20 in a circumferential direction. The regulator11 is constructed by fixing a circuit board 11 a mounted with electroniccomponents to a heat sink 11 b. The regulator 11 is mounted by fittingthe heat sink 11 b onto the brush holder 22 such that the circuit board11 a is housed inside a circuit housing portion 22 b of the brush holder22. Thus, the heat sink 11 b of the regulator 11 faces an inner wallsurface of an end portion of the rear bracket 2.

In the opening portion 30 of the rear bracket 2, a pair of side walls 31are formed facing each other parallel to the axial direction of theshaft 6. Grooves 31 a parallel to the axial direction are formed in thefacing inner wall surfaces of the pair of side walls 31. Moreover, anupper surface of a front-end wall of the opening portion 30 ispositioned in a common plane with lower surfaces of the grooves 31 a ofthe side walls 31, and an upper surface of a rear-end wall is positionedin a substantially common plane with upper surfaces of the side walls31.

The cap 40 is made of a polybutylene terephthalate (PBT) resin, and isconstituted by: a main body portion 41 formed into a general box shape;a handle 42 disposed so as to extend from a first end of the main bodyportion 41; flange portions 43 disposed so as to extend from first andsecond side portions, respectively, of the main body portion 41;protruding portions 44 disposed so as to protrude from an inner wallsurface of the main body portion 41; and an engaging portion 45 forpreventing dislodgment disposed so as to protrude from a first end ofthe inner wall surface of the main body portion 41. This cap 40 ismounted to the opening portion 30 by holding the handle 42, insertingthe flange portions 43 into the grooves 31 a, sliding the cap 40 until asecond end portion of the main body portion 41 comes into contact with arear-end surface 30 b of the opening portion 30, and then elasticallyengaging the engaging portion 45 in the front-end surface 30 a of theopening portion 30. Thus, the opening portion 30 is covered by the cap40. The protruding portions 44 press an upper surface of the cover 29radially inward, compressing the packing on the cover 29.

During replacement of the brushes 21, the elastic engagement between theengaging portion 45 and the front-end surface 30 a of the openingportion 30 is released by holding the handle 42 and pulling upward in aradial direction (upward in FIG. 1), then the cap 40 is pulled out bysliding it toward a front end of the opening portion 30. Next, afterremoving the cover 29, the screws 28 are removed, and the brushassemblies 24 are pulled out of the brush insertion apertures 22 a.Then, the brushes 21 of new brush assemblies 24 are inserted into thebrush insertion apertures 22 a, the brush terminals 25 are securelyfastened to the terminals 23 by means of the screws 28 fromlongitudinally (radially) outside the brushes 21, and the cover 29 isfitted into the head portion of the brush holder 22. Next, thereplacement of the brushes 21 is completed by inserting the cap 40 intothe opening portion 30 in a similar manner.

In the automotive alternator according to Embodiment 1, because theopening portion 30 is formed in the portion of the case 3 (the rearbracket 2) facing the cover 29 of the brush holding apparatus 20 and thecap 40 is mounted so as to cover the opening portion 30, the brushes 21can be replaced by removing the cap 40, removing the cover 29, thenremoving the screws 28 and replacing each of the brush assemblies 24,making it unnecessary to dismantle the case 3.

Because the cap 40 is mounted by insertion into the opening portion 30,tools such as screw drivers, etc., are not required for removing andreplacing the cap 40, improving the brush replacement operation.

Because the cap 40 is mounted by inserting the flange portions 43 whilesliding in the grooves 31 a of the side walls 31, removal andreplacement of the cap 40 can be performed simply by pushing or pullingthe cap 40 in one direction, improving the brush replacement operation.

When an automotive alternator is mounted to an automotive vehicle, thereis clear space in the axial direction of the automotive alternator.Because the sliding direction of this cap 40 is aligned with the axialdirection of the shaft 6, space for removal of the cap 40 is ensured,further improving the brush replacement operation.

Because the cap 40 is made of the PBT resin and has elasticity, theengaging portion 45 of the cap 40 engages the front-end surface 30 a ofthe opening portion 30 elastically, preventing the cap 40 fromdislodging due to vibration, etc. Because the handle 42 is formedintegrally on the cap 40, handling of the cap 40 is facilitated.Furthermore, because the protruding portions 44 are formed on the cap 40and the protruding portions 44 press on the cover 29 when the cap 40 ismounted to the opening portion 30, the packing on the cover 29 is in acompressed state, improving the waterproofing of the brush holdingapparatus 20.

Moreover, Embodiment 1 above has been explained for a case in which theflange portions 43 are slidably inserted into the grooves 31 a and thecap 40 is secured to the opening portion 30 by elastically engaging theengaging portion 45 in the front-end surface 30 a of the opening portion30, but the method for inserting the cap 40 into the opening portion 30is not limited to this.

For example, the cap 40 may also be secured to the opening portion 30 bydisposing protrusions on the flange portions 43, disposing recessportions in inner wall surfaces of the grooves 31 a, and inserting theprotrusions into the recess portions when mounting the cap 40 to theopening portion 30.

The width of the grooves 31 a may also be made narrow in such a way thatthe cap 40 is secured to the opening portion 30 by press-fitting theflange portions 43. Leaf springs may also be mounted to the grooves 31 ain such a way that when the cap 40 is mounted to the opening portion 30,the flange portions 43 is secured by the force of the leaf springs. Inthose cases, it is not necessary to prepare the cap 40 using the PBTresin; a metal material can be used.

Furthermore, in Embodiment 1 above, the protruding portions 44 aremolded integrally when the cap 40 is molded using the PBT resin, but anelastic material such as a leaf spring or a silicone resin, for example,may also be fixed to the inner wall surface of the cap as a protrudingportion after molding the cap.

Embodiment 2

FIG. 13 is a plan showing a cap used in an automotive alternatoraccording to Embodiment 2 of the present invention, FIG. 14 is a sideelevation of the cap shown in FIG. 13 viewed from direction A, FIG. 15is a side elevation of the cap shown in FIG. 13 viewed from direction B,FIG. 16 is a perspective showing a rear bracket of the automotivealternator according to Embodiment 2 of the present invention with thecap mounted, FIG. 17 is a cross section taken along line XVII—XVII inFIG. 16 viewed from the direction of the arrows, and FIG. 18 is aperspective showing the rear bracket of the automotive alternatoraccording to Embodiment 2 of the present invention with the cap removed.

In Embodiment 2, at rear-end ends of side portions of a rectangularopening portion 30A in the rear bracket 2, a pair of side walls 31A areformed facing each other parallel to the axial direction of the shaft 6.Grooves 31 a parallel to the axial direction are formed in the facinginner wall surfaces of the pair of side walls 31A. An engaging aperture30 c is disposed through a front-end wall of the opening portion 30A.Moreover, an upper surface of a bracket-shaped wall constituted by thefront-end wall and the front-end ends of the side walls of the openingportion 30A is positioned in a common plane with lower surfaces of thegrooves 31 a of the side walls 31A, and an upper surface of a rear-endwall is positioned in a substantially common plane with upper surfacesof the side walls 31A.

The cap 50 is made of a PBT resin, and is constituted by: a flat,rectangular main body portion 51 having a generally U-shaped curvedportion 51 a formed into a central portion; a handle 52 disposed so asto extend from a first end of the main body portion 51; flange portions53 formed by first and second side portions of the main body portion 51;protruding portions 54 disposed so as to protrude from first and secondend positions of the curved portion 51 a on an inner wall surface of themain body portion 51; and an engaging portion 55 for preventingdislodgment disposed so as to protrude from a first end of the innerwall surface of the main body portion 51.

This cap 50 is held by the handle 52, the flange portions 53 areinserted into the grooves 31 a, and the cap 50 is slid until a secondend portion of the main body portion 51 comes into contact with arear-end surface 30 b of the opening portion 30A. Then, the curvedportion 51 a is deformed elastically by pressing the handle 52 towardthe rear-end surface 30 b of the opening portion 30A. The engagingportion 55 is inserted inside the opening portion 30A by lowering thehandle 52 radially downward (toward the shaft 6) with the curved portion51 a deformed elastically, and then pressure on the handle 52 isreleased. Thus, the curved portion 51 a returns to its original state, ahook 55 a on the engaging portion 55 is inserted into the engagingaperture 30 c in the front-end wall of the opening portion 30A, and thecap 50 is mounted to the opening portion 30A with the engaging portion55 engaged elastically in the front-end wall of the opening portion 30A.Thus, the opening portion 30A is covered by the cap 50. The protrudingportions 54 press an upper surface of the cover 29 radially inward,compressing the packing 29 a on the cover 29.

During replacement of the brushes 21, the hook 55 a of the engagingportion 55 is pulled out of the engaging aperture 30 c by holding thehandle 52 and pressing it toward the rear-end surface 30 b of theopening portion 30A to deform the curved portion 5 a elastically. Theengaging portion 55 is pulled out of the opening portion 30A by raisingthe handle 52 radially upward (away from the shaft 6) with the curvedportion 51 a deformed elastically, and then pressure on the handle 52 isreleased. Thus, the curved portion 51 a returns to its original state.Then, the handle 52 is held and the cap 50 is pulled out by sliding ittoward a front end of the opening portion 30A. Next, after removing thecover 29, the screws 28 are removed, and the brush assemblies 24 arepulled out of the brush insertion apertures 22 a. Then, the brushes 21of new brush assemblies 24 are inserted into the brush insertionapertures 22 a, the brush terminals 25 are securely fastened to theterminals 23 by means of the screws 28 from longitudinally (radially)outside the brushes 21, and the cover 29 is fitted into the head portionof the brush holder 22. Next, the replacement of the brushes 21 iscompleted by inserting the cap 50 into the opening portion 30A in asimilar manner.

Consequently, similar effects to those in Embodiment 1 above can also beachieved in Embodiment 2.

Furthermore, in Embodiment 2, because the hook 55 a of the engagingportion 55 is inserted into the engaging aperture 30 c in the front-endwall of the opening portion 30A, the cap 50 is reliably prevented fromdislodging due to vibration, etc.

Embodiment 3

FIG. 19 is a plan showing a cap used in an automotive alternatoraccording to Embodiment 3 of the present invention, FIG. 20 is a sideelevation of the cap shown in FIG. 19 viewed from direction A, FIG. 21is a side elevation of the cap shown in FIG. 19 viewed from direction B,FIG. 22 is a perspective showing a rear bracket of the automotivealternator according to Embodiment 3 of the present invention with thecap mounted, and FIG. 23 is a perspective showing the rear bracket ofthe automotive alternator according to Embodiment 3 of the presentinvention with the cap removed.

In Embodiment 3, at rear-end ends of side portions of a rectangularopening portion 30B in the rear bracket 2, a pair of side walls 31B areformed facing each other parallel to the axial direction of the shaft 6.Grooves 31 a parallel to the axial direction are formed in the facinginner wall surfaces of the pair of side walls 31B. Moreover, an uppersurface of a bracket-shaped wall constituted by the front-end wall andthe front-end ends of the side walls of the opening portion 30B ispositioned in a common plane with lower surfaces of the grooves 31 a ofthe side walls 31B, and an upper surface of a rear-end wall ispositioned in a substantially common plane with upper surfaces of theside walls 31B.

The cap 60 is made of a PBT resin, and is constituted by: a main bodyportion 61 formed into a flat rectangular shape; a handle 62 disposed soas to extend from a first end of the main body portion 61; flangeportions 63 formed by first and second side portions of the main bodyportion 61; protruding portions 64 disposed so as to protrude from aninner wall surface of the main body portion 61; and an engaging portion65 for preventing dislodgment disposed so as to protrude from a firstend of the inner wall surface of the main body portion 61.

This cap 60 is held by the handle 62, the flange portions 63 areinserted into the grooves 31 a, and the cap 60 is slid until a secondend portion of the main body portion 61 comes into contact with arear-end surface 30 b of the opening portion 30B. Then, a first end ofthe main body portion 61 is deformed elastically into a convex shape bypressing the handle 62 toward the rear-end surface 30 b of the openingportion 30B. The engaging portion 65 is inserted inside the openingportion 30B by lowering the handle 62 radially downward (toward theshaft 6) with the main body portion 61 deformed elastically, and thenpressure on the handle 62 is released. Thus, the main body portion 61returns to its original state and the cap 60 is mounted to the openingportion 30B with the engaging portion 65 engaged elastically in afront-end surface 30 a of the opening portion 30B. Thus, the openingportion 30B is covered by the cap 60. The protruding portions 64 pressan upper surface of the cover 29 radially inward, compressing thepacking on the cover 29.

During replacement of the brushes 21, the first end of the main bodyportion 61 is deformed elastically into a convex shape by holding thehandle 62 and pressing it toward the rear-end surface 30 b of theopening portion 30B. The engaging portion 65 is pulled out of theopening portion 30B by raising the handle 62 radially upward (away fromthe shaft 6) with the main body portion 61 deformed elastically, andthen pressure on the handle 62 is released. Thus, the main body portion61 returns to its original state. Then, the handle 62 is held and thecap 60 is pulled out by sliding it toward a front end of the openingportion 30B. Next, after removing the cover 29, the screws 28 areremoved, and the brush assemblies 24 are pulled out of the brushinsertion apertures 22 a. Then, the brushes 21 of new brush assemblies24 are inserted into the brush insertion apertures 22 a, the brushterminals 25 are securely fastened to the terminals 23 by means of thescrews 28 from longitudinally (radially) outside the brushes 21, and thecover 29 is fitted into the head portion of the brush holder 22. Next,the replacement of the brushes 21 is completed by inserting the cap 60into the opening portion 30B in a similar manner.

Consequently, similar effects to those in Embodiment 1 above can also beachieved in Embodiment 3.

Furthermore, in Embodiment 3, because the engaging portion 65 iselastically engaged in the front-end surface 30 a of the opening portion30B by means of the force of recovery of the elastic deformation of themain body portion 61, the cap 60 is reliably prevented from dislodgingdue to vibration, etc.

Embodiment 4

FIG. 24 is a plan showing a cap used in an automotive alternatoraccording to Embodiment 4 of the present invention, FIG. 25 is a sideelevation of the cap shown in FIG. 24 viewed from direction A, FIG. 26is a side elevation of the cap shown in FIG. 24 viewed from direction B,FIG. 27 is a perspective showing a rear bracket of the automotivealternator according to Embodiment 4 of the present invention with thecap mounted, and FIG. 28 is a perspective showing the rear bracket ofthe automotive alternator according to Embodiment 4 of the presentinvention with the cap removed.

In Embodiment 4, three surfaces of opening edge portions of arectangular opening portion 30C in the rear bracket 2 except for arear-end surface 30 b are formed in a bracket shape so as to bepositioned in a common plane, grooves 31 b parallel to the axialdirection being formed in outer wall surfaces of a pair of side walls31C.

A cap 70 is made of a PBT resin, and is constituted by: a main bodyportion 71 formed into a bracket shape; engaging portions 72 forpreventing dislodgment disposed so as to extend inward from lower endportions of first and second sides 71 a of the main body portion 71;first and second handles 73 disposed so as to extend outward from thefirst and second sides 71 a of the main body portion 71; and a stopper74 for preventing dislodgment disposed so as to protrude from a firstend of the inner wall surface of the main body portion 71.

This cap 70 is placed over the opening portion 30C from a radialdirection with the first and second handles 73 held and pulled such thatthe first and second sides 71 a of the main body portion 71 are spreadapart, and then the pulling of the handles 73 is stopped. Thus, thefirst and second sides 71 a of the main body portion 71 return to theiroriginal state, placing the engaging portions 72 in contact with anouter wall surface of a pair of side walls 31C of the opening portion30C. Next, the handles 73 are held, and the main body portion 71 ispressed radially downward. Then, when the engaging portions 72 reach thegrooves 31 b, they are fitted into the grooves 31 b by the force ofrecovery of the main body portion 71. Thus, the opening portion 30C iscovered by the cap 70. The engaging portions 72 are engaged elasticallyin the grooves 31 b, preventing the cap 70 from dislodging. Furthermore,forward movement of the cap 70 is prevented by the stopper 74 cominginto contact with a front-end surface 30 a of the opening portion 30C,and rearward movement of the cap 70 is prevented by a second end surfaceof the cap 70 coming into contact with the rear-end surface 30 b of theopening portion 30C.

During replacement of the brushes 21, the first and second handles 73are held and pulled such that the first and second sides 71 a of themain body portion 71 are spread apart, pulling the engaging portions 72out of the grooves 31 b. Then, the main body portion 71 is removed fromthe opening portion 30C by holding the handles 73 and pulling the mainbody portion 71 radially upward. Next, after removing the cover 29, thescrews 28 are removed, and the brush assemblies 24 are pulled out of thebrush insertion apertures 22 a. Then, the brushes 21 of new brushassemblies 24 are inserted into the brush insertion apertures 22 a, thebrush terminals 25 are securely fastened to the terminals 23 by means ofthe screws 28 from longitudinally (radially) outside the brushes 21, andthe cover 29 is fitted into the head portion of the brush holder 22.Next, the replacement of the brushes 21 is completed by inserting thecap 70 into the opening portion 30C in a similar manner.

Consequently, similar effects to those in Embodiment 1 above can also beachieved in Embodiment 4.

Furthermore, in Embodiment 4, it goes without saying that protrudingportions for pressing the cover 29 may also be disposed on an inner wallsurface of the main body portion 71 of the cap 70.

Moreover, in each of the above embodiments, the cap is made of a PBTresin, but the cap is not limited to the PBT resin, and for example, afire resistant resin such as a polyethylene terephthalate (PET), apolyphenylene sulfide (PPS), a polyamide, etc., can be used. In thatcase, a cap having even more superior fire resistance can be obtained ifglass fiber is added.

Furthermore, the cap does not necessarily have to be made of a resin andmay also be made of a metal such as a stainless alloy, etc.

As explained above, according to one aspect of the present invention,there is provided an automotive alternator including:

a case;

a shaft, first and second ends of the shaft being rotatably supported inthe case;

a rotor fixed to the shaft and rotatably disposed inside the case;

a slip ring fixed to the shaft;

a stator fixed to the case so as to surround the rotor;

a brush holder through which a brush insertion aperture is disposed andwhich a cover is fitted into a head portion of the brush holder, thebrush holder being disposed inside the case such that an aperturedirection of the brush insertion aperture is perpendicular to an axialdirection of the shaft;

a brush disposed so as to be held inside the brush insertion apertureand slide in contact with the slip ring;

an opening portion formed in a portion of the case facing the cover; and

a cap insertably mounted to the opening portion, simplifying removal andreplacement of the cap, thereby providing an automotive alternatorenabling the brush to be changed without dismantling the case.

The cap may be slidably mounted to the opening portion, improving theoperation of removing and replacing the cap.

A sliding direction of the cap may be parallel to an axial direction ofthe shaft, providing clear space in the sliding direction of the capwhen the automotive alternator is mounted to an automotive vehicle,thereby improving the operation of removing and replacing the cap.

Protruding portions may be formed on an inner wall surface of the cap,the protruding portions being constructed so as to press the covertoward the shaft when the cap is mounted to the opening portion,improving waterproofing of the brush holder, thereby suppressing theoccurrence of failure due to exposure of the brush to moisture.

A handle may be formed integrally on the cap, improving the handling ofthe cap, thereby improving the operation of removing and replacing thecap.

Engaging portions for engaging the opening portion and preventingdislodgment may be formed integrally on the cap, reliably preventing thecap from falling off due to vibration.

The cap may be made of an elastic member, enabling the cap to be securedto the opening portion using the elasticity of the cap, thereby reducingdamage to the opening portion and the cap.

The cap may be made of a resin, enabling cost reductions.

1. An automotive alternator comprising: a case; a shaft, first andsecond ends of said shaft being rotatably supported in said case; arotor fixed to said shaft and rotatably disposed inside said case; aslip ring fixed to said shaft; a stator fixed to said case so as tosurround said rotor; a brush holder through which a brush insertionaperture is disposed and onto which a cover is fitted into a headportion of said brush holder, said brush holder being disposed insidesaid case such that an aperture direction of said brush insertionaperture is perpendicular to an axial direction of said shaft; a brushdisposed so as to be held inside said brush insertion aperture insliding contact with said slip ring; an opening portion formed in aportion of said case facing said cover; and a cap insertably mounted tosaid opening portion.
 2. The automotive alternator according to claim 1,wherein: said cap is slidably mounted to said opening portion.
 3. Theautomotive alternator according to claim 2, wherein: a sliding directionof said cap is parallel to an axial direction of said shaft.
 4. Theautomotive alternator according to claim 1, wherein: protruding portionsare formed on an inner wall surface of said cap, said protrudingportions being constructed so as to press said cover toward said shaftwhen said cap is mounted to said opening portion.
 5. The automotivealternator according to claim 1, wherein: a handle is formed integrallyon said cap.
 6. The automotive alternator according to claim 1, wherein:engaging portions for engaging said opening portion and preventingdislodgment are formed integrally on said cap.
 7. The automotivealternator according to claim 1, wherein: said cap is made of an elasticmember.
 8. The automotive alternator according to claim 1, wherein: saidcap is made of a resin.